The suit in Alameda County Superior Court is among about 40 cases nationwide alleging workplace violations against Wal-Mart, and the first to go to trial. Wal-Mart, which earned $10 billion last year, settled a lawsuit in Colorado for $50 million that contains similar allegations to California's class action. The company also is accused of paying men more than women in a federal lawsuit pending in San Francisco federal court.

The workers in the class-action suit are owed more than $66 million plus interest, attorney Fred Furth told the 12 jurors and four alternates.

"I will prove the reason they did this was for the God Almighty dollar," Furth said in his opening statement.

Nine jurors must side with the plaintiffs to prevail. Millions of dollars also are sought to punish the company for the alleged wrongdoing.

The case concerns a 2001 state law, which is among the nation's most worker friendly. Employees who work at least six hours must have a 30-minute, unpaid lunch break. If they do not get that, the law requires they are paid for an additional hour of pay.

The lawsuit covers former and current employees in California from 2001 to 2005.

Wal-Mart declined to give an opening statement, reserving its right to give one later. Its lawyers also declined comment.

In court documents, the Bentonville, Ark., company claims that workers did not demand penalty wages on a timely basis. Wal-Mart adds that it did pay some employees their penalty pay and, in 2003, most workers agreed to waive their meal periods as the law allows.

The Bentonville, Ark.-based company also says some violations were minor, such as demanding employees punch back in from lunch and work during their meal breaks. In essence, workers were provided a shorter meal period than the law allows.

The case does not claim that employees were forced to work off the clock during their lunch breaks.

The lawsuit was brought in 2001 by a handful of San Francisco-area former Wal-Mart employees, and took four years of legal wrangling to get to trial. During that time, Wal-Mart produced internal audits that plaintiffs' lawyers maintain showed the company knew it was not granting meal breaks on thousands of occasions.

That 2000 audit was given to top-level executives, according to evidence submitted to jurors Monday.

One company document called results of the audit "a chronic problem." A one-week review of company policies showed thousands of instances in which workers were not given a meal break in accordance with the law, according to the documents provided to the jury.

"This is Wal-Mart auditing Wal-Mart," Furth said.

On Tuesday, as many as three plaintiffs are expected to testify in a trial that will last weeks.

Several lawyers representing out-of-state Wal-Mart workers in class action lawsuits were in the gallery. Karin Kramer, a lawyer suing Wal-Mart on behalf of 50,000 Washington state company workers, said suing Wal-Mart is a gargantuan task.

"They can afford and do fight you on every single issue," she said.

Shares of Wal-Mart rose 14 cents to close at $44.01 Monday on the New York Stock Exchange.